A lift transmitting component of the pre-cited type configured as a roller tappet for activating a tappet push rod of a gas exchange valve train of an internal combustion engine is known from the generic document U.S. Pat. No. 5,099,807. The roller tappet comprises a cam-activated roller, mounted through a rolling bearing on the bearing pin that is fixed with radially widened front ends both by positive engagement and by force-locking in a reception bore of the tappet housing. The radial deformation of the front ends is effected by gyratory calking and the calked material of the bearing pin is displaced as a circular ring into a chamfer at the opening of the reception bore.
An alternative manner of fixing the bearing pin in the housing is disclosed, for example, in the likewise generic document U.S. Pat. No. 4,628,874 that, in addition to a roller tappet, also discloses a lift transmitting component configured as a roller finger lever. In both cases, the bearing pin for the roller is fixed in the reception bore of the respective housing by the fact that the material of the front ends of the bearing pin is displaced by a calking method radially outwards into a circumferential undercut situated within the reception bore.
Undercuts of the aforesaid type are also proposed for a roller tappet disclosed in U.S. Pat. No. 5,385,124. However, these undercuts do not serve to receive calked material of the bearing pin but for the reception of circlips that serve as positively acting axial stops for the non-deformed front ends of a bearing pin that is float-mounted in the reception bore.
A common feature of all the lift transmitting components proposed in the cited documents is that, with the aim of achieving wear resistance, their bearing pins are hardened in the region of their roller raceways. But if a bearing pin is calked, it is imperative for its front ends to be adequately soft in view of the material flow that is concomitant with the calking process. Such a bearing pin with non-uniform hardness values along its length, however, can only be realized through complex and, thus, cost-intensive heat treating methods. A further drawback of bearing pins whose front ends have only a low hardness arises from the fact that their calked ends must be fixed in the reception bore not only by positive engagement but also by force-locking. The reason for this is that, in the case of a bearing pin that is not fixed by force-locking in the reception bore and comes into rotation by the friction forces of the rotating roller, the soft ends of the bearing pin would be subject to contact friction with the housing on their periphery and would suffer a loss of their axial securing function and thus shear off. A fixing of the bearing pin in the reception bore not only by positive engagement but also by force-locking can pose a problem in cases in which the housing of the lift transmitting component has to meet special shape requirements as is the case with the initially cited cylindrical roller tappets. As a rule, these roller tappets are mounted in their longitudinal guides with a lash of just a few micrometers, so that a deformation of the housing, generally configured with thin walls in the region of the roller, would lead to an impermissibly large non-circularity of the housing due to the radially widened reception bore resulting from the calking of the bearing pin.
As proposed in the cited document U.S. Pat. No. 5,385,124, it is certainly possible to circumvent this chain of drawbacks by using a completely core-hardened bearing pin deformed on its front ends, float-mounted in its reception bore and fixed axially through positive engagement by means of circlips. Nonetheless, even in this case, there still remains the cost-increasing extra expenditure for the circlips and their assembly as well as for making the undercuts in the housing for receiving the circlips.